The field of the present invention generally relates to medical devices, systems and methods, and more particularly relates to light sources including, but not limited to, illumination sources used during surgical or other medical procedures.
Typically, surgical illumination is performed using white light sources. These sources of light are often based on xenon light engines that provide broad spectral response across most of the visible spectrum. In the last few years more LED (light emitting diode) light engines have become commercially available. The primary reason for this change has been for economic reasons. The cost of running an LED light engine is far less than a xenon light engine since bulbs do not need to be replaced.
A majority of the LED light engines currently on the market, such as Arthrex Synergy, utilize white light LED blue or UV phosphorous pumped dye. These light engines provide high color temperature and relatively high Color Rendering Index (CRI). CRI is a quantitative measure of a light source's ability to show the colors of a target accurately in comparison with an ideal or natural light source such as daylight. A high CRI is therefore typically desirable. There are also RGB (red, green, and blue) LED light sources such as the Stryker L9000, for example, that generate simulated white light by combining red, green, and blue LEDs. Since the light provided by this type of light source only has three spectral bands, which are separated by gaps between the bands, the CRI is often very low, and hence tissue illuminated with this light may not have the same color rendition when compared to xenon illumination. It would therefore be desirable to provide RGB LED or other light sources with higher CRI so that color rendition can be closer to natural colors.
In addition to color rendition, another challenge during surgery is that much of the tissue may become “bleached out” when high intensity pure white light sources are used. When the light is bright, many of the various tissue colors can become blended and color contrast dramatically reduced. It would therefore be desirable to create a light source that can enhance contrast by increasing absorption in certain tissues or reducing reflection in others, thereby improving tissue differentiation.
To improve contrast and tissue targeting, some manufacturers have used techniques to provide specific wavelengths of light to enhance visualization of specific tissue when a fluorescent injectable dye (e.g., indocyanine green (ICG)), is used. For example, filtered light, lasers and monochrome LEDs have been used in conjunction with injectable dye to illuminate tissue and cause it to fluoresce. However, this technique may complicate surgery when the light source is operating in a narrow wavelength and other tissues are not well seen. This may be the case when the entire image is monochrome in order to highlight the fluorescent tissue. Other systems try to address this challenge by adding imaging or computer imaging to combine the RGB image with the fluorescent image to provide a fused practical imaging environment.
For at least these reasons, it would be desirable to provide light sources which can provide a version of white light that may be used with endoscopic procedures, or in an open, direct visualization surgical procedure, without any image processing. It would also be desirable to provide a multispectral light engine that is based on multiple single color LEDs or other illumination elements working together to generate a specific spectral output. It would further be desirable to provide a light engine that allows the user to have certain pre-set settings that can easily be selected, based on surgical procedure, for example, in order to enhance the visibility of certain tissues and provide greater contrast without having to manually adjust the light source. At least some of these, and other objectives, may be addressed by various embodiments of the invention disclosed herein.